“Is it necessary to use condoms/dental dams for oral sex? What if it is not used? Does that guarantee transmission of sexually transmitted infections?”

Thanks for this great question! Oral sex has become a very common sexual activity in the Western world. For instance, most U.S. adults under age 50 say that they have given and/or received oral sex in the past year in the form of fellatio or cunnilingus, a number that has increased significantly during the past few decades.

However, despite being such a widely practiced activity, very few people use condoms or other barriers for protection when they do it. Consider this: in one study of 1,373 U.K. students, 56% reported having had oral sex before—but, of them, only 17% had ever used a condom for this act [1]. Moreover, just 2% reported using condoms consistently during oral sex.

Public health officials are concerned about this state of affairs because those who do not use condoms or barriers regularly during oral sex expose themselves to the possibility of both spreading and contracting numerous sexually transmitted infections. For instance, it is possible to spread bacterial infections such as chlamydia and gonorrhea during oral sex (indeed, both of these infections have the potential to take hold in the throat). Viral infections such as herpes and HPV can be transmitted as well (e.g., if someone with an oral herpes infection performs oral sex, they can potentially give their partner genital herpes; likewise, someone with a genital herpes infection can potentially transfer that infection to their partner’s oral area). Oral sex also creates an opportunity for pubic lice to spread to moustaches and beards.

To be perfectly clear, this should not be taken to mean that failure to use condoms or dental dams during oral sex “guarantees” transmission of sexual infections—rather, I would simply say that this increases the risk of infection. We cannot really say for sure what the exact likelihood of transmission is for a given STI for any sexual activity.

So why do so few people use condoms during oral sex? Research finds that there are many contributing factors [1]. For instance, it is a matter of pleasure for some—as with other forms of sex, some people feel that using condoms during oral sex makes it less pleasurable for both giver and receiver. Other reasons include (but are not limited to) never having given condom use a thought during this activity or just not wanting to do it.

So should you be using condoms and dental dams during oral sex? If you want to reduce your risk of spreading and contracting STIs as much as possible, then it's something you should be thinking about. However, it is important to note that using condoms or dental dams does not guarantee protection. I say this because condoms are often used incorrectly and sometimes fail. In addition, sometimes barriers do not cover all of the infected parts of the skin. All forms of sex carry some degree of risk no matter how you do it, so it is best to think of condom and barrier use in terms of risk reduction, not risk elimination.